add pf_ring patches for kernel and libpcap

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@2266 3c298f89-4303-0410-b956-a3cf2f4a3e73

2 files changed, 614 insertions, 1 deletions

diff --git a/openwrt/package/libpcap/Makefile b/openwrt/package/libpcap/Makefile
index fa79e7461..c7dfd9991 100644
--- a/openwrt/package/libpcap/Makefile
+++ b/openwrt/package/libpcap/Makefile
@@ -57,7 +57,7 @@ $(PKG_BUILD_DIR)/.built:
 	rm -rf $(PKG_INSTALL_DIR)
 	mkdir -p $(PKG_INSTALL_DIR)
 	$(MAKE) -C $(PKG_BUILD_DIR) \
-		CCOPT="$(TARGET_CFLAGS)" \
+		CCOPT="$(TARGET_CFLAGS) -I$(BUILD_DIR)/linux/include" \
 		DESTDIR="$(PKG_INSTALL_DIR)" \
 		all install
 	touch $@
diff --git a/openwrt/package/libpcap/patches/110-pf_ring.patch b/openwrt/package/libpcap/patches/110-pf_ring.patch
new file mode 100644
index 000000000..1d5124fac
--- /dev/null
+++ b/openwrt/package/libpcap/patches/110-pf_ring.patch
@@ -0,0 +1,613 @@
+diff -urN libpcap.old/pcap-int.h libpcap.dev/pcap-int.h
+--- libpcap.old/pcap-int.h	2003-12-15 02:42:24.000000000 +0100
++++ libpcap.dev/pcap-int.h	2005-10-22 23:20:12.220060500 +0200
+@@ -30,7 +30,7 @@
+  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+  * SUCH DAMAGE.
+  *
+- * @(#) $Header: /tcpdump/master/libpcap/pcap-int.h,v 1.55.2.4 2003/12/15 01:42:24 guy Exp $ (LBL)
++ * @(#) $Header: /export/home/ntop/PF_RING/userland/libpcap-0.8.1-ring/pcap-int.h,v 1.2 2004/11/25 09:58:00 deri Exp $ (LBL)
+  */
+ 
+ #ifndef pcap_int_h
+@@ -46,6 +46,8 @@
+ #include <packet32.h>
+ #endif /* WIN32 */
+ 
++#define RING /* L.Deri */
++
+ /*
+  * Savefile
+  */
+@@ -93,6 +95,57 @@
+ #endif
+ };
+ 
++/* **************************** */
++
++#ifdef  RING
++
++#include <unistd.h>
++#include <sys/mman.h>
++#include <errno.h>
++#include <sys/poll.h>
++
++#define PAGE_SIZE         4096
++
++#define HAVE_PCAP
++#include <linux/ring.h>
++#endif
++
++#ifdef RING
++
++#define E1000_RXD_STAT_DD       0x01    /* Descriptor Done */
++
++struct e1000_rx_desc {
++  u_int64_t buffer_addr; /* Address of the descriptor's data buffer */
++  u_int16_t length;     /* Length of data DMAed into data buffer */
++  u_int16_t csum;       /* Packet checksum */
++  u_int8_t status;      /* Descriptor status */
++  u_int8_t errors;      /* Descriptor Errors */
++  u_int16_t special;
++};
++
++/* Transmit Descriptor */
++struct e1000_tx_desc {
++    u_int64_t buffer_addr;       /* Address of the descriptor's data buffer */
++    union {
++        u_int32_t data;
++        struct {
++            u_int16_t length;    /* Data buffer length */
++            u_int8_t cso;        /* Checksum offset */
++            u_int8_t cmd;        /* Descriptor control */
++        } flags;
++    } lower;
++    union {
++        u_int32_t data;
++        struct {
++            u_int8_t status;     /* Descriptor status */
++            u_int8_t css;        /* Checksum start */
++            u_int16_t special;
++        } fields;
++    } upper;
++};
++
++#endif
++
+ struct pcap {
+ #ifdef WIN32
+ 	ADAPTER *adapter;
+@@ -121,6 +174,14 @@
+ 	u_char *bp;
+ 	int cc;
+ 
++#ifdef RING
++        /* PF_RING */
++	char *ring_buffer, *ring_slots;
++	int  ring_fd;
++	FlowSlotInfo *slots_info;
++        u_int page_id, slot_id, pkts_per_page;
++        u_int poll_sleep;
++#endif
+ 	/*
+ 	 * Place holder for pcap_next().
+ 	 */
+diff -urN libpcap.old/pcap-linux.c libpcap.dev/pcap-linux.c
+--- libpcap.old/pcap-linux.c	2003-11-21 11:20:46.000000000 +0100
++++ libpcap.dev/pcap-linux.c	2005-10-22 23:43:59.726120250 +0200
+@@ -27,7 +27,7 @@
+ 
+ #ifndef lint
+ static const char rcsid[] _U_ =
+-    "@(#) $Header: /tcpdump/master/libpcap/pcap-linux.c,v 1.98.2.4 2003/11/21 10:20:46 guy Exp $ (LBL)";
++    "@(#) $Header: /export/home/ntop/PF_RING/userland/libpcap-0.8.1-ring/pcap-linux.c,v 1.2 2004/11/25 09:58:00 deri Exp $ (LBL)";
+ #endif
+ 
+ /*
+@@ -83,7 +83,7 @@
+ #ifdef HAVE_DAG_API
+ #include "pcap-dag.h"
+ #endif /* HAVE_DAG_API */
+-	  
++
+ #include <errno.h>
+ #include <stdlib.h>
+ #include <unistd.h>
+@@ -217,6 +217,83 @@
+ 	= { 1, &total_insn };
+ #endif
+ 
++#define RING /* L.Deri */
++#define SAFE_RING_MODE /*
++			  Copy the bucket in order to avoid kernel
++			  crash if the application faults
++		       */
++
++#ifdef RING
++unsigned char *write_register;
++static struct pcap_stat ringStats;
++u_long  numPollCalls = 0, numReadCalls = 0;
++
++#define POLL_SLEEP_STEP         10 /* ns = 0.1 ms */
++#define POLL_SLEEP_MIN        POLL_SLEEP_STEP
++#define POLL_SLEEP_MAX        1000 /* ns */
++#define POLL_QUEUE_MIN_LEN     500 /* # packets */
++
++#ifdef SAFE_RING_MODE
++static char staticBucket[2048];
++#endif
++
++
++/* ******************************* */
++
++int pcap_set_cluster(pcap_t *handle, u_int clusterId) {
++  return(handle->ring_fd ? setsockopt(handle->ring_fd, 0, SO_ADD_TO_CLUSTER,
++				      &clusterId, sizeof(clusterId)): -1);
++}
++
++/* ******************************* */
++
++int pcap_remove_from_cluster(pcap_t *handle) {
++  return(handle->ring_fd ?
++	 setsockopt(handle->ring_fd, 0, SO_REMOVE_FROM_CLUSTER, NULL, 0) : -1);
++}
++
++/* ******************************* */
++
++int pcap_set_reflector(pcap_t *handle, char *reflectorDevice) {
++  return(handle->ring_fd ?
++	 setsockopt(handle->ring_fd, 0, SO_SET_REFLECTOR,
++		    &reflectorDevice, strlen(reflectorDevice)) : -1);
++}
++
++/* ******************************* */
++
++static int set_if_promisc(const char *device, int set_promisc) {
++  int sock_fd;
++  struct ifreq ifr;
++
++  if(device == NULL) return(-3);
++
++  sock_fd = socket(PF_PACKET, SOCK_RAW, htons(ETH_P_ALL));
++  if(sock_fd <= 0) return(-1);
++  
++  memset(&ifr, 0, sizeof(ifr));
++  strncpy(ifr.ifr_name, device, sizeof(ifr.ifr_name));
++  if(ioctl(sock_fd, SIOCGIFFLAGS, &ifr) == -1) {  
++    close(sock_fd);
++    return(-2);
++  }	  
++
++  if(set_promisc) {
++    if((ifr.ifr_flags & IFF_PROMISC) == 0) ifr.ifr_flags |= IFF_PROMISC;
++  } else {
++    /* Remove promisc */
++    if((ifr.ifr_flags & IFF_PROMISC) != 0) ifr.ifr_flags &= ~IFF_PROMISC;    
++  }
++  
++  if(ioctl(sock_fd, SIOCSIFFLAGS, &ifr) == -1) 
++    return(-1);
++  
++  close(sock_fd);
++  return(0);
++}
++
++#endif
++
+ /*
+  *  Get a handle for a live capture from the given device. You can
+  *  pass NULL as device to get all packages (without link level
+@@ -258,6 +335,138 @@
+ 	handle->snapshot	= snaplen;
+ 	handle->md.timeout	= to_ms;
+ 
++#ifdef RING
++	handle->ring_fd = handle->fd = socket(PF_RING, SOCK_RAW, htons(ETH_P_ALL));
++
++	printf("Open RING [fd=%d]\n", handle->ring_fd);
++
++	if(handle->ring_fd > 0) {
++	  struct sockaddr sa;
++	  int             rc;
++	  u_int memSlotsLen;
++
++	  err = 0;
++	  sa.sa_family   = PF_RING;
++	  snprintf(sa.sa_data, sizeof(sa.sa_data), "%s", device);
++	  rc = bind(handle->ring_fd, (struct sockaddr *)&sa, sizeof(sa));
++
++	  if(rc == 0) {
++
++
++	    handle->md.device = strdup(device);
++	    handle->ring_buffer = (char *)mmap(NULL, PAGE_SIZE,
++					       PROT_READ|PROT_WRITE,
++					       MAP_SHARED,
++					       handle->ring_fd, 0);
++
++	    if(handle->ring_buffer == MAP_FAILED) {
++	      sprintf(ebuf, "mmap() failed");
++	      return (NULL);
++	    }
++
++	    handle->slots_info = (FlowSlotInfo *)handle->ring_buffer;
++	    if(handle->slots_info->version != RING_FLOWSLOT_VERSION) {
++	      snprintf(ebuf, PCAP_ERRBUF_SIZE, "Wrong RING version: "
++		      "kernel is %i, libpcap was compiled with %i\n",
++		      handle->slots_info->version, RING_FLOWSLOT_VERSION);
++	      return (NULL);
++	    }
++	    memSlotsLen = handle->slots_info->tot_mem;
++	    munmap(handle->ring_buffer, PAGE_SIZE);
++
++	    handle->ring_buffer = (char *)mmap(NULL, memSlotsLen,
++					      PROT_READ|PROT_WRITE,
++					      MAP_SHARED, handle->ring_fd, 0);
++
++	    if(handle->ring_buffer == MAP_FAILED) {
++	      sprintf(ebuf, "mmap() failed");
++	      return (NULL);
++	    }
++
++	    handle->slots_info   = (FlowSlotInfo *)handle->ring_buffer;
++	    handle->ring_slots = (char *)(handle->ring_buffer+sizeof(FlowSlotInfo));
++
++	    /* Safety check */
++	    if(handle->slots_info->remove_idx >= handle->slots_info->tot_slots)
++	      handle->slots_info->remove_idx = 0;
++
++	    handle->page_id = PAGE_SIZE, handle->slot_id = 0,
++	      handle->pkts_per_page = 0;
++
++	    if(0) {
++	      int i;
++	      
++	      for(i=0; i<handle->slots_info->tot_slots; i++) {
++		unsigned long idx = i*handle->slots_info->slot_len;
++		FlowSlot *slot = (FlowSlot*)&handle->ring_slots[idx];
++		
++		printf("RING: Setting RING_MAGIC_VALUE into slot %d [displacement=%lu]\n", i, idx);
++		slot->magic = RING_MAGIC_VALUE; slot->slot_state = 0;
++		printf("RING: slot[%d]: magic=%d, slot_state=%d\n", 
++		       slot->magic, slot->slot_state);
++	      }
++	    }
++
++
++	    /* Set defaults */
++	    handle->linktype = DLT_EN10MB;
++	    handle->offset = 2;
++
++	    printf("RING (%s): tot_slots=%d/slot_len=%d/"
++		   "insertIdx=%d/remove_idx=%d/dropped=%d\n",
++		   device,
++		   handle->slots_info->tot_slots,
++		   handle->slots_info->slot_len,
++		   handle->slots_info->insert_idx,
++		   handle->slots_info->remove_idx,
++		   handle->slots_info->tot_lost);
++
++	    ringStats.ps_recv = handle->slots_info->tot_read;
++	    ringStats.ps_drop = handle->slots_info->tot_lost;
++
++	    if(promisc) {
++	      struct ifreq ifr;
++
++	      err = 0;
++	      memset(&ifr, 0, sizeof(ifr));
++	      strncpy(ifr.ifr_name, device, sizeof(ifr.ifr_name));
++	      if (ioctl(handle->fd, SIOCGIFFLAGS, &ifr) == -1) {
++		snprintf(ebuf, PCAP_ERRBUF_SIZE,
++			 "ioctl: %s", pcap_strerror(errno));
++		err = 1;
++	      }
++
++	      if(err == 0) {
++		if ((ifr.ifr_flags & IFF_PROMISC) == 0) {
++		  /*
++		   * Promiscuous mode isn't currently on,
++		   * so turn it on, and remember that
++		   * we should turn it off when the
++		   * pcap_t is closed.
++		   */
++
++		  ifr.ifr_flags |= IFF_PROMISC;
++		  if (ioctl(handle->fd, SIOCSIFFLAGS, &ifr) == -1) {
++		    snprintf(ebuf, PCAP_ERRBUF_SIZE,
++			     "ioctl: %s", pcap_strerror(errno));
++		    err = 1;
++		  }
++		}
++
++		if(err == 0)
++		  handle->md.clear_promisc = 1;
++	      }
++	    }
++
++	    if(err == 0)
++	      goto open_open_live_final;
++	  }
++
++	  /* Don't put 'else' above... */
++	  close(handle->ring_fd);
++	  /* Continue without ring support */
++	}
++#endif
+ 	/*
+ 	 * NULL and "any" are special devices which give us the hint to
+ 	 * monitor all devices.
+@@ -397,6 +606,9 @@
+ 		return NULL;
+ 	}
+ 
++#ifdef RING
++ open_open_live_final:
++#endif
+ 	/*
+ 	 * "handle->fd" is a socket, so "select()" and "poll()"
+ 	 * should work on it.
+@@ -449,6 +661,120 @@
+ 	int			packet_len, caplen;
+ 	struct pcap_pkthdr	pcap_header;
+ 
++#ifdef RING
++	if(handle->ring_buffer != NULL) {
++	  u_int idx, numRuns = 0, ptrAddr;
++	  FlowSlot *slot;
++	  
++	  slot = (FlowSlot*)&handle->ring_slots[handle->slots_info->remove_idx*handle->slots_info->slot_len];
++
++	  while(1) {
++	    u_int32_t queuedPkts;
++
++	    if(handle->slots_info->tot_insert >= handle->slots_info->tot_read)
++	      queuedPkts = handle->slots_info->tot_insert - handle->slots_info->tot_read;
++	    else
++	      queuedPkts = handle->slots_info->tot_slots + handle->slots_info->tot_insert - handle->slots_info->tot_read;
++
++	    if(queuedPkts && (slot->slot_state == 1)) {
++	      char *bucket = &slot->bucket;
++
++#ifdef RING_MAGIC
++	      if(slot->magic != RING_MAGIC_VALUE) {
++		printf("==>> Bad Magic [remove_idx=%u][insert_idx=%u][ptrAddr=%u]\n",
++		       handle->slots_info->remove_idx,
++		       handle->slots_info->insert_idx, 
++		       ptrAddr);
++		slot->magic = RING_MAGIC_VALUE;
++	      }
++#endif
++
++
++	      handle->md.stat.ps_recv++;
++
++#ifdef SAFE_RING_MODE
++	      {
++		struct pcap_pkthdr *hdr = (struct pcap_pkthdr*)bucket;
++		int bktLen = hdr->caplen;
++
++		if(bktLen > sizeof(staticBucket))
++		  bktLen = sizeof(staticBucket);
++
++		memcpy(staticBucket, &bucket[sizeof(struct pcap_pkthdr)], bktLen);
++
++#ifdef RING_DEBUG
++		printf("==>> [remove_idx=%u][insert_idx=%u][ptrAddr=%u]\n",
++		       handle->slots_info->remove_idx,
++		       handle->slots_info->insert_idx, 
++		       ptrAddr);
++#endif
++
++		callback(userdata, hdr, staticBucket);
++	      }
++#else
++	      callback(userdata,
++		       (const struct pcap_pkthdr*)bucket,
++		       (const u_char*)&bucket[sizeof(struct pcap_pkthdr)]);
++#endif
++
++	      if(handle->slots_info->remove_idx >= (handle->slots_info->tot_slots-1)) {
++		handle->slots_info->remove_idx = 0;
++		handle->page_id = PAGE_SIZE, handle->slot_id = 0, handle->pkts_per_page = 0;
++	      } else {
++		handle->slots_info->remove_idx++;
++		handle->pkts_per_page++, handle->slot_id += handle->slots_info->slot_len;
++	      }
++
++	      handle->slots_info->tot_read++;
++	      slot->slot_state = 0;
++
++	      return(1);
++	    } else {
++	      struct pollfd pfd;
++	      int rc;
++
++	      /* Sleep when nothing is happening */
++	      pfd.fd      = handle->ring_fd;
++	      pfd.events  = POLLIN|POLLERR;
++	      pfd.revents = 0;
++
++#ifdef RING_DEBUG
++	      printf("==>> poll [remove_idx=%u][insert_idx=%u][loss=%d][queuedPkts=%u]"
++		     "[slot_state=%d][tot_insert=%u][tot_read=%u]\n",
++		     handle->slots_info->remove_idx,
++		     handle->slots_info->insert_idx,
++		     handle->slots_info->tot_lost, 
++		     queuedPkts, slot->slot_state,
++		     handle->slots_info->tot_insert,
++		     handle->slots_info->tot_read);
++	      #endif
++	      
++#ifdef RING_DEBUG
++	      printf("==>> poll @ [remove_idx=%u][slot_id=%u]\n", handle->slots_info->remove_idx, handle->slot_id);
++#endif
++	      errno = 0;
++	      rc = poll(&pfd, 1, -1);
++#ifdef RING_DEBUG
++	      printf("==>> poll returned %d [%s][errno=%d][break_loop=%d]\n",
++		     rc, strerror(errno), errno, handle->break_loop);
++#endif
++	      numPollCalls++;
++
++	      if(rc == -1) {
++		if(errno == EINTR) {
++		  if(handle->break_loop) {
++		    handle->break_loop = 0;
++		    return(-2);
++		  } else
++		    return(0);
++		} else
++		  return(-1);
++	      }
++	    }
++	  } /* while() */
++	}
++#endif
++
+ #ifdef HAVE_PF_PACKET_SOCKETS
+ 	/*
+ 	 * If this is a cooked device, leave extra room for a
+@@ -688,6 +1014,22 @@
+ 	socklen_t len = sizeof (struct tpacket_stats);
+ #endif
+ 
++#ifdef RING
++	if(handle->ring_fd > 0) {
++	  stats->ps_recv = handle->slots_info->tot_read-ringStats.ps_recv;
++	  stats->ps_drop = handle->slots_info->tot_lost-ringStats.ps_drop;
++
++	  printf("RING: numPollCalls=%d [%.1f packets/call]\n",
++		 numPollCalls, (float)stats->ps_recv/(float)numPollCalls);
++	  printf("RING: [tot_pkts=%u][tot_read=%u][tot_lost=%u]\n", 
++		 handle->slots_info->tot_pkts,
++		 handle->slots_info->tot_read,
++		 handle->slots_info->tot_lost);
++
++	  return(0);
++	}
++#endif
++
+ #ifdef HAVE_TPACKET_STATS
+ 	/*
+ 	 * Try to get the packet counts from the kernel.
+@@ -879,6 +1221,11 @@
+ 		}
+ 	}
+ 
++
++#ifdef RING
++	if(handle->ring_fd <= 0) can_filter_in_kernel = 0;
++#endif
++
+ 	if (can_filter_in_kernel) {
+ 		if ((err = set_kernel_filter(handle, &fcode)) == 0)
+ 		{
+@@ -1348,7 +1695,7 @@
+ 			memset(&mr, 0, sizeof(mr));
+ 			mr.mr_ifindex = device_id;
+ 			mr.mr_type    = PACKET_MR_PROMISC;
+-			if (setsockopt(sock_fd, SOL_PACKET,
++			if (setsockopt(sock_fd, 0 /* SOL_PACKET */,
+ 				PACKET_ADD_MEMBERSHIP, &mr, sizeof(mr)) == -1)
+ 			{
+ 				snprintf(ebuf, PCAP_ERRBUF_SIZE,
+@@ -1425,10 +1772,11 @@
+ 
+ 	/* Any pending errors, e.g., network is down? */
+ 
+-	if (getsockopt(fd, SOL_SOCKET, SO_ERROR, &err, &errlen) == -1) {
+-		snprintf(ebuf, PCAP_ERRBUF_SIZE,
+-			"getsockopt: %s", pcap_strerror(errno));
+-		return -2;
++	if ((getsockopt(fd, PF_RING, SO_ERROR, &err, &errlen) == -1)
++	    && (getsockopt(fd, SOL_SOCKET, SO_ERROR, &err, &errlen) == -1)) {
++	  snprintf(ebuf, PCAP_ERRBUF_SIZE,
++		   "getsockopt: %s", pcap_strerror(errno));
++	  return -2;
+ 	}
+ 
+ 	if (err > 0) {
+@@ -1482,6 +1830,13 @@
+ 	struct pcap	*p, *prevp;
+ 	struct ifreq	ifr;
+ 
++#ifdef RING
++	if(handle->ring_buffer != NULL) {
++	  munmap(handle->ring_buffer, handle->slots_info->tot_mem);
++	  handle->ring_buffer = NULL;
++	}
++#endif
++
+ 	if (handle->md.clear_promisc) {
+ 		/*
+ 		 * We put the interface into promiscuous mode; take
+@@ -1698,11 +2053,11 @@
+ 	}
+ 
+ 	/* Any pending errors, e.g., network is down? */
+-
+-	if (getsockopt(fd, SOL_SOCKET, SO_ERROR, &err, &errlen) == -1) {
+-		snprintf(ebuf, PCAP_ERRBUF_SIZE,
+-			"getsockopt: %s", pcap_strerror(errno));
+-		return -1;
++	if((getsockopt(fd, PF_RING, SO_ERROR, &err, &errlen) == -1)
++	   && (getsockopt(fd, SOL_SOCKET, SO_ERROR, &err, &errlen) == -1)) {
++	  snprintf(ebuf, PCAP_ERRBUF_SIZE,
++		   "getsockopt: %s", pcap_strerror(errno));
++	  return -1;
+ 	}
+ 
+ 	if (err > 0) {
+@@ -1924,8 +2279,11 @@
+ 	 * the filtering done in userland even if it could have been
+ 	 * done in the kernel.
+ 	 */
+-	if (setsockopt(handle->fd, SOL_SOCKET, SO_ATTACH_FILTER,
+-		       &total_fcode, sizeof(total_fcode)) == 0) {
++	printf("pcap[setsockopt(%d)]\n", 0);
++	if (setsockopt(handle->fd, 0 /* SOL_SOCKET */,
++		       SO_ATTACH_FILTER,
++		       &total_fcode,
++		       sizeof(total_fcode)) == 0) {
+ 		char drain[1];
+ 
+ 		/*
+@@ -1933,6 +2291,9 @@
+ 		 */
+ 		total_filter_on = 1;
+ 
++#ifdef RING
++		if(!handle->ring_fd) {
++#endif
+ 		/*
+ 		 * Save the socket's current mode, and put it in
+ 		 * non-blocking mode; we drain it by reading packets
+@@ -1955,12 +2316,15 @@
+ 				return -2;
+ 			}
+ 		}
+-	}
++#ifdef RING
++		}
++#endif
++}
+ 
+ 	/*
+ 	 * Now attach the new filter.
+ 	 */
+-	ret = setsockopt(handle->fd, SOL_SOCKET, SO_ATTACH_FILTER,
++	ret = setsockopt(handle->fd, 0 /* SOL_SOCKET */, SO_ATTACH_FILTER,
+ 			 fcode, sizeof(*fcode));
+ 	if (ret == -1 && total_filter_on) {
+ 		/*
+@@ -1993,7 +2357,8 @@
+ 	/* setsockopt() barfs unless it get a dummy parameter */
+ 	int dummy;
+ 
+-	return setsockopt(handle->fd, SOL_SOCKET, SO_DETACH_FILTER,
+-				   &dummy, sizeof(dummy));
++	return setsockopt(handle->fd, handle->ring_fd > 0 ? PF_RING : SOL_SOCKET,
++			  SO_DETACH_FILTER,
++			  &dummy, sizeof(dummy));
+ }
+ #endif